This invention relates to novel concentrated photographic fixer additive and concentrated photographic fixing compositions. It also relates to methods of using these concentrated compositions in photoprocessing. Thus, this invention relates to the photographic industry and to photochemical processing in particular.
The conventional image-forming process of silver halide photography includes imagewise exposure of a photographic silver halide recording material to actinic radiation (such as actinic light), and the eventual manifestation of a useable image by wet photochemical processing of that exposed material. A fundamental step of photochemical processing is the treatment of the material with one or more developing agents to reduce silver halide to silver metal. With black-and-white photographic materials, the metallic silver usually comprises the image. With color photographic materials, the useful image consists of one or more images in organic dyes produced from an oxidized developing agent formed wherever silver halide is reduced to metallic silver.
To obtain useful color images, it is usually necessary to remove all of the silver from the photographic element after color development. This is sometimes known as xe2x80x9cdesilveringxe2x80x9d. Removal of silver is generally accomplished by oxidizing the metallic silver, and then dissolving it and undeveloped silver halide with a xe2x80x9csolventxe2x80x9d or fixing agent in what is known as a fixing step. Oxidation is achieved with an oxidizing agent, commonly known as a bleaching agent.
Fixing is typically carried out using a fixing composition that includes one or more fixing agents such as thiosulfate salts. Both ammonium and sodium thiosulfate salts are known. Fixing solutions containing ammonium ions are preferred for providing more rapid fixing, but they present environmental concerns. Thus, fixing solutions containing sodium ions, while slower, are also advantageous.
Color photographic silver halide materials often contain various sensitizing dyes that extend the inherent photosensitivity of the photosensitive silver halide emulsions to electromagnetic radiation. One important class of such sensitizing dyes are carbocyanine sensitizing dyes that are commonly included in silver halide emulsion layers in photographic silver halide films, for example in color reversal photographic silver halide films (films normally used to provide positive color images).
Many photographic silver halide elements contain residual sensitizing dyes after photoprocessing. In some cases, the level of retained sensitizing dyes is inconsequential and thus, unobservable. In other instances, however, the high level of retained sensitizing dye results in undesirably high dye stain (or unwanted color) in the elements.
A number of solutions have been proposed for this problem, including the inclusion of water-soluble stilbene optical brighteners in the color developer solution [as described for example, in Research Disclosure, 20733, page 268, July, 1981 and U.S. Pat. No. 4,587,195 (Ishikawa et al)], the bleach-fixing solution [as described for example, in JP 1-062642 (published Mar. 9, 1989), JP 1-158443 (published Jun. 21, 1989), and U.S. Pat. No. 5,043,253 (Ishikawa)], or the stabilizing solution used at the end of the photoprocessing [as described for example in U.S. Pat. No. 4,895,786 (Kurematsu et al)].
Concentrated and working strength fixing compositions that solve the residual dye stain problem are described in U.S. Pat. No. 6,013,425 (Craver et al). These compositions contain certain triazinylstilbene compounds as stain reducing agents. While they are quite effective in this regard, keeping them in solution may require the presence of one or more water-soluble stabilizing compounds such as glycols.
The problems with residual sensitizing dyes have also been satisfactorily addressed by incorporating certain stain reducing agents into one or more working strength photographic processing compositions. These compounds are described in copending and commonly assigned U.S. Ser. No. 09/464,551 filed Dec. 16, 1999 by Goswami et al now U.S. Pat. No. 6,153,365, and U.S. Ser. No. 09/464,961 filed Dec. 16, 1999 by Goswami et al now U.S. Pat. No. 6,153,364, as colorless or slightly yellow compounds having an extended planar xcfx80 system that is devoid of a diarninostilbene fragment or fused triazole nuclei. While these compounds can be incorporated into various photoprocessing compositions, it is preferred to include them in concentrated photographic fixing compositions.
However, when we attempted to incorporate some of these stain reducing agents into concentrated solutions such as concentrated fixing solutions, we found that some of them did not pass our rigorous solubility tests. For example, many of them showed unacceptable solubility even when organic solvents were added, insolubility in solution at low temperature for lengthy times, or insolubility in concentrated fixing composition.
There remains a need in the photographic industry for a way to decrease the dye stains resulting from retained sensitizing dye during photoprocessing using concentrated processing compositions that meet all manufacturing, customer use, and storage stability requirements.
The problems with known photographic compositions and photoprocessing methods are overcome with the use of the present invention.
In one embodiment, the present invention provides a concentrated aqueous fixer additive composition consisting essentially of:
a) at least 0.01 mol/l of a compound having the structure I 
xe2x80x83wherein R is carboxy or sulfo, m is an integer of from 0 to 5 and n is an integer of from 2 to 7, and
b) water.
This concentrated fixer additive composition can be used to advantage to prepare the concentrated aqueous fixing composition of this invention, which composition has a pH of 8 or less and consists essentially of:
a) at least 2 mol/l of a photographic fixing agent,
b) at least 0.0001 mol/l of a compound represented by Structure I noted above, and
c) water.
Once the concentrated aqueous fixing composition is prepared, it can be used to prepare an aqueous working strength fixer or replenisher. Thus, this invention further provides a method of making an aqueous working strength fixing composition comprising the steps of:
A) preparing the concentrated aqueous photographic fixing composition noted above by mixing the concentrated fixer additive composition described above with the photographic fixing agent, and
B) diluting the resulting concentrated aqueous photographic fixing composition from about 2 to about 15 times.
This invention further provides a method for providing a color image comprising:
A) bleaching an imagewise exposed and color developed color photographic silver halide element, and
B) prior to or after step A, fixing the photographic element with an aqueous working strength photographic fixing composition prepared from the concentrated fixing composition described above.
Step B of this method can also be carried out by diluting, at least 2 times, the concentrated aqueous photographic fixing composition described above.
The advantages of this invention are several. The concentrated fixer additive composition can be manufactured, provided and stored for considerable time without precipitation of the stain reducing agent, thereby reducing the costs associated with volume and storage. The fixer additive composition volume can be small enough so as not to significantly dilute the concentrate to which it is added. Because there is no need for solvents other than water, there is no additional environmental burden. The resulting working strength fixing composition is also highly stable, and can be used to advantage to reduce stain from retained sensitizing dyes in processing photographic silver halide elements.
Only the specific stain reducing agents represented by Structure I provide the desired stability in the concentrated compositions of this invention. Thus, the compounds of Structure I meet the following minimal stability standards:
a) they are soluble at 33 g in 500 ml of water,
b) they have low temperature solubility that is determined by placing 100 ml aqueous samples of the compounds in closed containers and holding them individually it at 0xc2x0 F. (xe2x88x9218xc2x0 C.), 20xc2x0 F. (xe2x88x927xc2x0 C.), 30xc2x0 F. (xe2x88x921 C.), 40xc2x0 F. (4xc2x0 C.), 50xc2x0 F. (10xc2x0 C.) and 70xc2x0 F. (21xc2x0 C.) for 14 days and then observing the samples 24 hours later for signs of precipitation or other observable changes (for example color, presence of haze, or phase separation), and
c) they cause no precipitation at 33 g in a 18.9 liter volume of commercially available KODAK Fixer and Replenisher Process E-6 AR at room temperature for at least 3 days (preferably at least 10 days).
Working strength fixing compositions can be prepared in several ways using the present invention. The concentrated fixer additive composition can be added directly to a working strength composition containing a suitable fixing agent, or mixed with the appropriate fixing agents in appropriate amounts to form the concentrated aqueous fixing composition. This composition can then be diluted in an appropriate manner and used for photoprocessing.
The concentrated and working strength photographic fixing compositions described herein perform only one photoprocessing function, fixing. They do not perform a bleaching function, so the compositions are not bleach-fixing compositions. The language xe2x80x9cconsisting essentially ofxe2x80x9d is intended to indicate that no photographic bleaching agents (such as iron chelates, peroxides or persulfates) are intentionally added to the fixing composition of this invention. Any small amounts of bleaching agents may be present merely because of carryover from previous photoprocessing baths.
The language xe2x80x9cconsisting essentially ofxe2x80x9d is also meant to exclude significant amounts of organic solvents such as solubilizing solvents in the fixing concentrates or fixer additive compositions of this invention. Such solvents may be present in small amounts that have no meaningful effect.
As used herein unless otherwise indicated, the term xe2x80x9cfixing compositionsxe2x80x9d refers to both the concentrated and working strength fixing compositions.
Useful fixing agents for photographic fixing compositions are well known. Examples of photographic fixing agents include, but not limited to, thiosulfates (for example sodium thiosulfate, potassium thiosulfate and ammonium thiosulfate), thiocyanates (for example sodium thiocyanate, potassium thiocyanate and ammonium thiocyanate), thioethers (such as ethylenebisthioglycolic acid and 3,6-dithia-1,8-octanediol), imides and thiourea. Thiosulfates and thiocyanates are preferred, and thiosulfates are more preferred. Ammonium thiosulfate is most preferred.
It is also known to use fixing accelerators in fixing compositions. Representative fixing accelerators include, but are not limited to, ammonium salts, guanidine, ethylenediamine and other amines, quaternary ammonium salts and other amine salts, thiourea, thioethers, thiols and thiolates. Examples of useful thioether fixing accelerators are described in U.S. Pat. No. 5,633,124 (Schmittou et al).
A critical component of the concentrated fixer additive and photographic fixing compositions of this invention is a spectral sensitizing dye stain reducing agent that is a 2,6-dinaphthylaminotriazine compound as represented by Structure I (or mixture thereof). These compounds have at least four sulfonate solubilizing groups attached to the naphthyl rings and specific substituents attached to the triazine ring.
The compounds useful in this invention can be represented by Structure I: 
wherein R is carboxy (or salt thereof) or sulfo (or salt thereof), m is an integer of from 0 to 5, and n is an integer of from 2 to 7. Preferably, R is carboxy, m is an integer of 1 to 2, and n is 2.
Representative compounds within Structure I are the following Compounds I-1 to I-7: 
Single compounds or mixtures thereof can also been used in the practice of this invention. Compound I-1 (or an alkali metal salt thereof) noted above is most preferred.
These 2,6-dinaphthylaminotriazine compounds can be prepared using the methods described for example in WO 97/10887. A representative synthesis of preferred Compound I-1 is provided below.
The concentrated fixer additive compositions of this invention have only two essential components: one or more compounds of Structure I and water. However, optional and nonessential components may be present if desired. Such components include buffers, sequestering agents, preservatives (such as sulfites), and other addenda that would be readily apparent to one skilled in the art.
While the concentrated fixing compositions of this invention have only three essential components: one or more fixing agents, one or more compounds of Structure I, and water, they can also include one or more of various nonessential addenda optionally but commonly used in such compositions for various purposes, including hardening agents, preservatives (such as sulfites or bisulfites), metal sequestering agents (such as polycarboxylic acids and organophosphonic acids), buffers, and fixing accelerators. The amounts of such addenda in the working strength compositions would be readily known to one skilled in the art. The amounts useful in the concentrate compositions would be readily apparent from the teaching included herein.
The desired pH of the fixing compositions of this invention is 8 or less, and can be achieved and maintained using any useful combination of acids and bases, as well as various buffers. The pH of the concentrated fixing composition can vary from that of the working strength fixing composition.
Other details of fixing compositions not explicitly described herein are considered well known in the art, and are described for example, in Research Disclosure publication 38957 (noted below), and publications noted therein in paragraph XX(B), incorporated herein by reference.
The following TABLE I shows the general and preferred pH and amounts of essential components of the concentrated additive composition and the fixing compositions of this invention. The preferred ranges are listed in parentheses ( ), and all of the ranges are considered to be approximate or xe2x80x9caboutxe2x80x9d in the upper and lower end points. During fixing, the actual concentrations can vary depending upon extracted chemicals in the composition, fixer replenishment rates, water losses due to evaporation and carryover from the preceding processing bath and carryover to the next processing bath. The working strength fixing composition concentrations are based on a dilution rate of from about 2 to about 15 of the concentrated fixing composition.
During fixing, the fixing composition in the processor may accumulate dissolved silver halide, and other substances that are extracted from the processed photographic element. Such materials, and particularly silver halide, can be removed using known means, such as ion exchange, electroysis, electrodialysis and precipitation.
Fixing can be carried out using a single working strength fixing composition bath (single stage), or multistage methods. Agitation or recirculation can also be used if desired. Fixing can also be carried out using any known method for contacting a fixing composition and the photographic element. Such methods include, but not limited to, immersing the photographic element in the working strength fixing composition, laminating a cover sheet containing the fixing composition to the photographic element, and applying the fixing composition by high velocity jet or spraying.
Since the fixing step is a separate step in an overall image-forming method, any processing sequence can be used for processing either black-and-white or color photographic elements. Representative processing sequences are described for example in Research Disclosure publication 308119, December 1989, publication 17643, December 1978, and publication 38957, September 1996. Research Disclosure is a publication of Kenneth Mason Publications Ltd., Dudley House, 12 North Street, Emsworth, Hampshire PO10 7DQ England. For example, in processing black-and-white photographic elements, fixing is usually preceded by a developing step, and may be followed with one or more washing or stabilizing steps.
Preferably, the compositions of the present invention are used to process color photographic elements, including but not limited to, color negative photographic films, color reversal photographic films, and color photographic papers. The general sequence of steps and conditions (times and temperatures) for processing are well known as Process C-41 and Process ECN-2 for color negative films, Process E-6 and Process K-14 for color reversal films, and Process RA-4 for color papers. The processing solutions used for the various processing steps in such processing sequences are also well known (except for the fixing steps carried out in this invention).
More preferably, the compositions are used to provide positive color images in color reversal photographic films. The typical sequence of steps includes first development (black-and-white development), reversal processing step, color developing, bleaching, fixing, and stabilizing. There may be various washing steps between other steps, as well as a pre-bleach step or conditioning step before bleaching. Alternatively, stabilizing can occur between color developing and bleaching. Many details of such processes are provided in U.S. Pat. No. 5,552,264 (Cullinan et al), incorporated herein by reference. Other details are provided in Research Disclosure, publication 38957 (noted above), and references noted therein.
Color reversal films are comprised of a support having thereon a plurality of photosensitive silver halide emulsion layers that can contain any conventional silver halide (or mixture thereof). Such films generally have silver halide emulsions having at least 1 mol % iodide based on total silver.
Useful supports are well known and include polyester films, polycarbonate films and cellulose acetate films. The silver halide layers include conventional binder materials, and other conventional addenda. Some specific commercially available color reversal photographic films that can be processed using this invention include EKTACHROME Color Reversal Films (Eastman Kodak Company), FUJICHROME Color Reversal Films (Fuji Photo Film Co., Ltd.), AGFACHROME Color Reversal Films (AGFA), KONICACHROME Color Reversal Films (Konica) and SCOTCHCHROME Color Reversal Films (3M Corporation).
The first developing step is usually carried out using a conventional black-and-white developing solution that can contain black-and-white developing agents, auxiliary co-developing agents, preservatives, antifoggants, anti-sludging agents, buffers and other conventional addenda.
Color developing is generally carried out using one or more conventional color developing agents, such as primary amino color developing agents. The color developing solution can also include various other conventional addenda including preservatives (including hydroxylamine and its derivatives), fluorescent dyes, sulfites, sequestering agents, corrosion inhibitors and buffers.
Bleaching is generally carried out using one or more bleaching agents that convert metallic silver to silver ions. Binary and ternary ferric complexes of aminopolycarboxylic acids are common bleaching agents, as well as persulfates and peroxides. Other components of the bleaching solution include buffers, halides and sequestering agents.
A photographic stabilizing step can be carried out using any dye stabilizing solution known in the art. Alternatively, a final rinsing step can be used.
For the fixing step of the method of this invention, the concentrated fixing composition of this invention can be diluted up 15 times, and preferably from 2 to 15 times (more preferably from 5 to 12 times), to provide a working strength or fixing replenishing composition. Dilution can be carried out during or prior to its use in the image formation process. In addition, the concentrated fixing composition can be added to the fixing solution bath, or to the fixer replenisher.
Fixing is generally carried out for conventional times and under conventional conditions. In addition, the fixing compositions of this invention can be used in what would be considered xe2x80x9crapidxe2x80x9d processing wherein the fixing step is carried out for as few as 10 seconds.
Processing can be carried out using any suitable processing equipment, including deep tank processors, and xe2x80x9clow volume thin tankxe2x80x9d processes including rack and tank and automatic tray designs, as described for example in U.S. Pat. No. 5,436,118 (Carli et al), and publications noted therein. Rotary tube processors can also be used for processing color reversal films.
The concentrated fixing composition of this invention is prepared by mixing the fixing agent and other fixing composition components (in appropriate amounts) with the concentrated additive composition of this invention. Alternatively, the Structure I compound can be added directly to the concentrated fixing composition.
The working strength composition can be prepared either by diluting the concentrated fixing composition appropriately with water and/or buffers, or by adding the concentrated fixing composition directly to the fixing bath or fixer replenisher.